Flowmaster is one of those exhaust companies that has never let us down. Their kits just sound good and are some of the most popular 2011 to 2014 F150 5.0L Cat-Back Exhaust Kits. Their most aggressive kit is part of their classic and utterly awesome American Thunder Series of exhaust systems, which are built from the ground up to add a deep, throaty roar to your engine. The American Thunder kits are already some of the most popular systems for the Mustang GT's 5.0L Coyote V8, so we were all itching to get this awesome kit up and running on our 2012 F150 5.0L FX4 Project Truck. Luckily, the American Thunder kit met and exceeded all of our expectations and was easily one of the better-sounding kits that we've put on our truck so far. What's even better, Flowmaster includes enough tubing to give you the option of either a straight rear exit or split side exit configuration that's perfect for anyone on the fence on how they want their truck to work.
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Our American Thunder install just wouldn't be an install at Stage 3 if we didn't head to Extreme Performance out in Goodyear, Arizona, for a little assistance from Chris, Marty, and anyone else who happened to be around. The good news about this kit is that it comes with tubing to git every F150 wheelbase, with some cutting, anyway. If there is any bad news (which there really isn't too much with this kit), it is a dual exit exhaust kit, so there is slightly more work than a single-exit system. That being said, Flowmaster's American Thunder Kit fit wonderfully and gave us no hassles.
The stock cat-back kit is built to keep your truck quiet and features both a forward resonator and mid-mounted muffler. The first step of our cat-back installation was to hit all the piping connections with penetrating oil to help make Kris's life much easier.
After letting the penetrating oil do some work, Chris removed the bolts holding the resonator pipe to both the muffler's pipe and our F150's mid-pipe, before completely removing the whole assembly.
With the resonator pipe out, Chris maneuvered the muffler tube and over-axle pipe out of its hangars, over the axle, and out of our truck.
When Chris had the stock exhaust system out, it was tome to start installing the Flowmaster kit. The first step was to bolt Flowmaster's inlet pipe to our truck's mid-pipe. Because our truck has a 145" wheelbase, we didn't need to cut or use the included extension pipe.
After the inlet pipe was in place, Chris slipped the hangar clamp over the tubing and through the forward OEM exhaust mount.
With the inlet tube and clamp on, Chris fit on a clamp and then installed the American Thunder muffler onto the system.
Then Chris fit clamps over the muffler's outlet tubes and connected the driver's side over-axle tube into the muffler, all while fitting its hangar through the upper bed rail exhaust mount.
Chris then went ahead and grabbed the outlet tubing for the driver's side and fit it on to the over-axle piping.
Now, he had left the exhaust hangar from our Solo Mach-X Install and testing on our truck. One, because that's the system we plan on keeping. Two, we hoped that any dual exhaust kit could just reuse it. Unfortunately, the Flowmaster kit has an exhaust hangar that's oriented sideways and it couldn't just be reused. More on that later.
Leaving the driver's side for a moment, Chris hooked up the passenger side over-axle assembly that also included the rearward hangar and installed a clamp.
Chris then went back to the driver's side and removed the Solo hangar for installation of Flowmaster's own hangar and mount.
With the mount squared away, Chris slipped the driver's side hangar through it.
Then Chris finished up he passenger side by fitting it's hangar through the rear OEM mount.
Now came the choice between the dual rear exit and dual side exit configurations. We're going to do both, just to show you the differences between setups, but first up is the straight dual rear exit. For this setup, you'll need the two "S" shaped tubes included in the kit. Chris installed them in just a couple of minutes.
After the two S-tubes were in place, Chris fit on their clamps.
Once the S-pipes were clamped on and looking aligned, Chris put on Flowmaster's included exhaust tips.
With everything all put together, all that was left to do was tighten down all the clamps while double-checking tip alignment as Chris moved from clamp to clamp.
So, if you're planning on setting your truck up for a dual rear exit, your install is complete.
For a dual side exit configuration, you'll need to grab the two 90° bends that Flowmaster includes in this kit instead of the two S-tubes. Naturally, this meant we had to remove both the exhaust tips and S-tubes that we already had installed.
After the S-tubes were removed, Chris installed the two 90° bends and clamped them down.
Then all Chris had to do was reinstall the exhaust tips.
So, if you're going for the dual side exit configuration, you install is complete.
The Flowmaster kit is a very good option for anyone on the fence about exhaust configuration. Not to mention, it sounds extremely good and clean. If we could level any real criticism at it, it's that tips aren't exactly the most aggressively-sized in the world. Then again, not everyone is into massive exhaust tips in the first place. Still, this is a very good kit and one of our current favorites.
